Sound design is extremely challenging, but these tips should help put you on the right track.
In most cases, indie filmmakers don't have the budget to hire someone to score their films. This means that you miss out on the benefit of having a score specifically designed to match what's going on up on screen, so you will have to figure out a way to do it with a piece of music that already exists. Though this is challenging, Kris Truini gives you a few helpful tips on how to pull it off, even if you don't have much experience working with music, scores, and soundtracks.
Truini shares a bunch of great tips in the video, but perhaps the most important one is this: the score/soundtrack should serve your story, not the other way around. In other words, the pacing of the edits in a scene should be more important than that of the music.
So, say you've got a song that has an absolutely amazing crescendo that occurs somewhere near the end of the piece, but the climax of the scene you're editing doesn't quite match up. You probably don't want to recut your clips to make them conducive to the song, because it could throw off the pacing of the scene, cut out important information that your audience needs to see/hear, or diminish the emotional effects of a certain shot(s).
We've all probably done this, I know I have, but one way to avoid doing it is by editing your shots first and then add music ones you're pretty confident with the cut. (It doesn't have to be super finalized.) Remember, story is king and your score should be designed to serve it.